The present disclosure relates to microstructures. More particularly, it relates to functionalized microscale three-dimensional devices and methods of making the same.
Three-dimensional (3D) micro/nanostructures with various shapes, architectures, and materials have recently been the subject of increased attention, because their dimensionality strongly influences their physical and chemical responses to surrounding environmental media as compared to two-dimensional (2D) micro/nanostructures. With regard to design, the advances in 3D, heterogeneously integrated, electronic devices (electrical networks) or 3D, artificially structured materials have accelerated the development of a new class of biomedical, electronic, and optical systems. Beyond integration technology which incorporates electronics into 3D structures, a free-standing, hollow-structured electronic device can have the potential for diverse applications. Specifically, with the integration of an electronic circuit, it can be used for multifunctional devices including sensors, smart chemical storage containers, telecommunications instruments, optical detectors, or programmable capsules in biomedicine. One notable impact in building such a device is the enhancement of versatility through the use of microscale patterning on a 3D dielectric window substrate, which can have advantages for the following applications: (i) In metamaterials, split-ring resonators (SRRs) defined on 3D dielectric structures produce isotropic, tailored anisotropic optical, or magnetic responses; (ii) Metal and/or semiconductor material patterns on the 3D dielectric substrate can also be used for building 3D electric circuits including sensors, transistors, and memory devices; and (iii) Free-standing hollow structures can be used as 3D containers (or encapsulation) for targeted drug delivery. In order to fully serve these functions, micro- and nanoscale surface patterning on the 3D dielectric structures plays a crucial role and, therefore, must be realized.
Conventional 3D fabrications are typically built using layer-by-layer (LBL) lithographic patterning methods, 3D printing, and/or self-aligned membrane projection lithography. With these traditional methods, development of a 3D, hollow, polyhedral structure has not been possible. In addition, limited surface patterning in micro-scale has been achieved. However, since the conventional lithographic process is a top-down strategy, surface patterning on a free-standing enclosed hollow structure (i.e., 3D micro-container) has not been realized.
Current approaches for building 3D micro-electronic devices via self-assembly have a critical limitation as follows: During the metal (or metal oxide) deposition and self-assembly processes, the spatial stress distribution on the materials can induce cracking, buckling, and/or delamination of the thin films.